(a) Field of the Invention
This invention concerns a class of pyrimido [2,1-c][1,4]benzoxazine derivatives. More specifically, this invention relates to 3-oxo-5H-pyrimido [2,1-c][1,4]benzoxazine derivatives, to a process for their preparation, to pharmaceutical formulations thereof and to methods for using the derivatives. The derivatives are useful for treating anaphylactic reactions and allergic conditions in mammals.
(b) Description of the Prior Art
A search of the chemical literature indicates that the compounds of this invention represent a novel tricyclic ring system. A number of related tricyclic compounds are described in the following reports: S. B. Kadin, U.S. Pat. No. 4,017,625, issued May 24, 1976; S. B. Kadin, U.S. Pat. No. 4,066,766, issued Jan. 3, 1978, S. B. Kadin and P. F. Moore, U.S. Pat. No. 4,031,217, issued June 21, 1977. These references disclose compounds which, like the compounds of this invention, are tricyclic; however, the tricyclic compounds in these references differ by being "carba" analogs.